AIDS-related studies in macaque models for antiretroviral or vaccine studies require well-characterized virus stocks. Because our original virus stock has remained limited, we urgently need a new virus stock for proposed or ongoing research projects. Thus, we have propagated a large quantity of uncloned SIVmne in primary PBMCs from na[unreadable]ve macaque donors. Before using the stock, we must determine its animal infectious dose (AID). In this project, the new SIVmne stock was titered and inoculated intravenously and intrarectally into Macaca fascicularis. The AID for intravenous inoculation is being studied in five juvenile macaques, one with a dose of 103 TCID and two each with doses of 102 and 10 TCID. The AID for intrarectal inoculation is being studied in three male and three female juvenile macaques, one male and one female each at doses of 104, 103, and 102 TCID. The minimum infectious doses and AIDS-like disease in inoculated macaques will be determined in the follo w-up study in the coming months. FUNDING NIH contract AI65311 and NIH grant RR00166.